Cmos image sensor including color microlens, and method for manufacturing same

ABSTRACT

The present invention relates to a CMOS image sensor including a color microlens, in which the color characteristics of a microlens are improved by replacing a microlens made of a transparent material with a material having characteristics similar to those of a color filter, and a manufacturing method thereof. In accordance with the CMOS image sensor including a color microlens and the manufacturing method thereof according to the present invention, color characteristics is improved. Since formation processes of a color filter and a microlens are performed at one time, additional processes for planarization and step difference adjustment are not necessary, so that an entire process is simplified. In the progress of light, since there is no interface between materials, reflection, refraction and the like are reduced, so that it is possible to increase light efficiency.

The present invention relates to a CMOS image sensor and a manufacturingmethod thereof, and particularly, to a CMOS image sensor including acolor microlens, in which the color characteristics of a microlens areimproved by replacing a microlens made of a transparent material with amaterial having characteristics similar to those of a color filter, anda manufacturing method thereof.

BACKGROUND ART

In general, an image sensor is a semiconductor device that converts anoptical image into an electrical signal, wherein a charge coupled device(CCD) is an element in which individual MOS (Metal-Oxide-Silicon)capacitors are very close to each other and a charge carrier is storedin the capacitor and is transported, and a CMOS image sensor is anelement employing a switching scheme in which MOS transistorscorresponding to the number of pixels are manufactured using a CMOStechnology using a control circuit and a signal processing circuit as aperipheral circuit and output is sequentially detected using the MOStransistors.

In such an image sensor, color filters are arranged above aphotodetection unit that receives light from an exterior and generatesand accumulates photocharge, and a color filter array (CFA) may includethree colors of red, green, and blue, or other colors.

Furthermore, in order to improve photosensitivity in the image sensor, alight collection technology for changing a path of incident light andcollecting the light to the photodetection unit has emerged. For suchlight collection, the image sensor uses a method for forming a microlenson the color filter.

Meanwhile, an image sensor using a conventional front-side illumination(hereinafter, referred to as FSI) scheme has a problem thatphotosensitivity is reduced by interference due to an interconnectionforming layer or crosstalk occurs. In order to solve such a problem, animage sensor using a back-side illumination (hereinafter, referred to asBSI) scheme has been recently used.

FIG. 1 is a diagram schematically illustrating a unit pixel of aconventional BSI CMOS image sensor.

As illustrated in FIG. 1, the unit pixel of the BSI CMOS image sensorhas a structure in which a metal interconnection layer 110, aphotodetection layer 120, an anti-reflective layer 130, a color filterlayer 140, an over-coating layer 150, and a microlens layer 160 aresequentially stacked.

In order to optimize the light efficiency of the CMOS image sensor, anover-coating layer (OCL), which is an additional layer for planarizationand step difference adjustment, is required to be provided above orbelow a color filter with respect to each pixel.

In such a case, an anti-reflective layer, an over-coating layer (OCL), acolor filter, an over-coating layer (OCL), and a microlens (ML) aresequentially connected to one another, so that a plurality of interfacesexist. Due to reflection or refraction of light occurring in theseinterfaces, light collection becomes difficult and loss of lightincident through an initial microlens actually occurs.

DISCLOSURE Technical Problem

Accordingly, the present invention has been made in an effort to solvethe problems occurring in the related art, and an object of the presentinvention is to provide a CMOS image sensor including a color microlens,which can improve the color characteristics of a microlens by replacinga microlens made of a transparent material with a material havingcharacteristics similar to those of a color filter, and a manufacturingmethod thereof.

Technical Solution

In order to achieve the above object, according to one aspect of thepresent invention, there is provided a CMOS image sensor including acolor microlens including: a photodetection layer formed over asemiconductor substrate and including at least one photodiode forreceiving light of at least one color; an anti-reflective layer formedover the photodetection layer; a color filter layer formed over theanti-reflective layer and including at least one color filter formed atpositions respectively corresponding to the at least one photodiode; anover-coating layer formed over the color filter layer and including atleast one over-coating formed at positions respectively corresponding tothe at least one color filter; and a color microlens layer formed overthe over-coating layer and including at least one color microlens formedat positions respectively corresponding to the at least one colorfilter.

In order to achieve the above object, according to another aspect of thepresent invention, there is provided a CMOS image sensor including acolor microlens including: a photodetection layer formed over asemiconductor substrate and including at least one photodiode forreceiving light of at least one color; an anti-reflective layer formedover the photodetection layer; and a color microlens layer serving as acolor filter formed over the anti-reflective layer and including a colormicrolens serving as at least one color filter formed at positionsrespectively corresponding to the at least one photodiode.

In order to achieve the above object, according to another aspect of thepresent invention, there is provided a CMOS image sensor including acolor microlens including: a photodetection layer formed over asemiconductor substrate and including at least one photodiode forreceiving light of at least one color; an anti-reflective layer formedover the photodetection layer; and a color microlens layer formed overthe anti-reflective layer and including at least one color microlensformed at positions respectively corresponding to the at least onephotodiode.

In order to achieve the above object, according to one aspect of thepresent invention, there is provided a manufacturing method of a CMOSimage sensor including a color microlens, including the steps of:forming a photodetection layer including at least one photodiode forreceiving light of at least one color over a semiconductor substrate;forming an anti-reflective layer over the photodetection layer; forminga color filter layer including at least one color filter at positionsrespectively corresponding to the at least one photodiode over theanti-reflective layer; forming an over-coating layer including at leastone over-coating formed at positions respectively corresponding to theat least one color filter over the color filter layer; and forming acolor microlens layer including at least one color microlens formed atpositions respectively corresponding to the at least one color filterover the over-coating layer.

In order to achieve the above object, according to another aspect of thepresent invention, there is provided a manufacturing method of a CMOSimage sensor including a color microlens, including the steps of:forming a photodetection layer including at least one photodiode forreceiving light of at least one color over a semiconductor substrate;forming an anti-reflective layer over the photodetection layer; andforming a color microlens layer serving as a color filter and includinga color microlens serving as at least one color filter formed atpositions respectively corresponding to the at least one photodiode overthe anti-reflective layer.

In order to achieve the above object, according to another aspect of thepresent invention, there is provided a manufacturing method of a CMOSimage sensor including a color microlens, including the steps of:forming a photodetection layer including at least one photodiode forreceiving light of at least one color over a semiconductor substrate;forming an anti-reflective layer over the photodetection layer; andforming a color microlens layer including at least one color microlensformed at positions respectively corresponding to the at least onephotodiode over the anti-reflective layer.

Advantageous Effects

In accordance with a CMOS image sensor including a color microlens and amanufacturing method thereof, a conventional microlens made of atransparent material is changed to a color microlens, so that aCRA/Shift equation can be separately used for each color, resulting inthe improvement of color characteristics.

Furthermore, since formation processes of a color filter and a microlensare performed at one time, additional processes for planarization andstep difference adjustment are not necessary, so that an entire processcan be simplified. In the progress of light, since there is no interfacebetween materials, reflection, refraction and the like are reduced, sothat it is possible to increase light efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, and other features and advantages of the presentinvention will become more apparent after a reading of the followingdetailed description taken in conjunction with the drawings, in which:

FIG. 1 is a diagram schematically illustrating a conventional BSI CMOSimage sensor;

FIG. 2 is a diagram schematically illustrating a CMOS image sensorincluding a color microlens according to the present invention;

FIG. 3 is a diagram schematically illustrating a CMOS image sensorincluding a color microlens according to another embodiment of thepresent invention;

FIG. 4 is a diagram schematically illustrating a CMOS image sensorincluding a color microlens according to further another embodiment ofthe present invention;

FIG. 5 is a flowchart illustrating a procedure of a manufacturing methodof a CMOS image sensor including a color microlens of FIG. 2;

FIG. 6 is a flowchart illustrating a procedure of a manufacturing methodof a CMOS image sensor including a color microlens of FIG. 3; and

FIG. 7 is a flowchart illustrating a procedure of a manufacturing methodof a CMOS image sensor including a color microlens of FIG. 4.

BEST MODE FOR THE INVENTION

Reference will now be made in greater detail to a preferred embodimentof the invention, an example of which is illustrated in the accompanyingdrawings. Wherever possible, the same reference numerals will be usedthroughout the drawings and the description to refer to the same or likeparts.

FIG. 2 is a diagram schematically illustrating a CMOS image sensorincluding a color microlens according to one embodiment of the presentinvention.

As illustrated in FIG. 2, a CMOS image sensor 200 including a colormicrolens according to the present invention has a structure in which ametal interconnection layer 210, a photodetection layer 220, ananti-reflective layer 230, a color filter layer 240, an over-coatinglayer 250, and a color microlens layer 260 are sequentially stacked.

The color microlens layer 260 is not made of a transparent material, andincludes a color microlens made of a material having characteristicsequal to or similar to those of the color filter layer 240. That is, thepresent invention is characterized in that a conventional generalmicrolens is changed to a color microlens to improve colorcharacteristics.

FIG. 3 is a diagram schematically illustrating a CMOS image sensorincluding a color microlens according to another embodiment of thepresent invention.

As illustrated in FIG. 3, a CMOS image sensor 300 including a colormicrolens according to the present invention has a structure in which ametal interconnection layer 310, a photodetection layer 320, ananti-reflective layer 330, and a color microlens layer 340 serving as acolor filter are sequentially stacked.

Referring to FIG. 3, in the CMOS image sensor 300 including a colormicrolens according to another embodiment of the present invention, acolor filter and a microlens are integrally formed with each other.

In this case, the heights of the color filter and the microlens for eachcolor may differ according to a sequence in which a color process isperformed. Furthermore, formation processes of the color filter and themicrolens are simultaneously performed, so that processes ofplanarization, step difference adjustment and the like can be omitted.

FIG. 4 is a diagram schematically illustrating a CMOS image sensorincluding a color microlens according to further another embodiment ofthe present invention.

As illustrated in FIG. 4, a CMOS image sensor 400 including a colormicrolens according to the present invention has a structure in which ametal interconnection layer 410, a photodetection layer 420, ananti-reflective layer 430, and a color microlens layer 440 aresequentially stacked.

Referring to FIG. 4, the CMOS image sensor 400 including a colormicrolens according to further another embodiment of the presentinvention includes only the microlens layer without a color filter,wherein the microlens layer is formed as a color microlens.

In this case, a focal distance of the color microlens may beappropriately adjusted in consideration of the structure in which thereis no color filter.

In FIG. 2, FIG. 3 and FIG. 4, examples in which the color filter array(CFA) and the microlens include three colors of red, green, and bluehave been described. However, the color filter array (CFA) and themicrolens may include three colors of yellow, magenta, and cyan, or ablack or white color.

Furthermore, each of the color filter array (CFA) and the microlens maybe differently combined, so that colors in a final sensor may bedifferently specified. That is, the blue of the color filter array (CFA)and the red of the microlens may be combined to each other to achievethe magenta, the green of the color filter array (CFA) and the blue ofthe microlens may be combined to each other to achieve the cyan, or thered of the color filter array (CFA) and the green of the microlens maybe combined to each other to achieve the yellow.

FIG. 5 is a flowchart illustrating a procedure of a manufacturing methodof the CMOS image sensor including a color microlens of FIG. 2.

As illustrated in FIG. 5, the manufacturing method of the CMOS imagesensor including a color microlens according to the present inventionincludes a step (S510) of forming a photodetection layer, a step (S520)of forming an anti-reflective layer, a step (S530) of forming a colorfilter layer, a step (S540) of forming an over-coating layer, and a step(S550) of forming a color microlens layer.

In the step (S510) of forming the photodetection layer, thephotodetection layer including at least one photodiode for receivinglight of at least one color is formed on a semiconductor substrate.

Next, in the step (S520) of forming the anti-reflective layer, theanti-reflective layer is formed on the photodetection layer.

In the step (S530) of forming the color filter layer, the color filterlayer including at least one color filter is formed at positions, whichrespectively correspond to the at least one photodiode, over theanti-reflective layer.

Then, in the step (S540) of forming the over-coating layer, theover-coating layer including at least one over-coating formed atpositions respectively corresponding to the at least one color filter isformed on the color filter layer.

Last, in the step (S550) of forming the color microlens layer, the colormicrolens layer including at least one color microlens formed atpositions respectively corresponding to the at least one color filter isformed on the over-coating layer.

Conventionally, all microlenses have been formed at one time. However,in the present invention, since the formation process of the colormicrolens layer is performed for each color, CRA and Shift Equation fora lens can be differently optimized for each color, so that it ispossible to improve optical properties.

Furthermore, in the conventional case, if light having passed through amicrolens layer does not match with CRA, crosstalk occurs. However, inthe case of the present invention, even though light having passedthrough a color microlens layer does not match with CRA, additionalfiltering can be performed in a lower color filter, so that it ispossible to improve crosstalk characteristics.

FIG. 6 is a flowchart illustrating a procedure of a manufacturing methodof the CMOS image sensor including a color microlens of FIG. 3.

As illustrated in FIG. 6, the manufacturing method of the CMOS imagesensor including a color microlens according to the present inventionincludes a step (S610) of forming a photodetection layer, a step (S620)of forming an anti-reflective layer, and a step (S630) of forming acolor microlens layer serving as a color filter.

The step (S610) of forming the photodetection layer and the step (S620)of forming the anti-reflective layer are equal to those described inFIG. 5.

In the step (S630) of forming the color microlens layer serving as acolor filter, the color microlens layer serving as a color filter andincluding a color microlens serving as at least one color filter formedat positions respectively corresponding to the at least one photodiodeis formed on the anti-reflective layer.

FIG. 7 is a flowchart illustrating a procedure of a manufacturing methodof the CMOS image sensor including a color microlens of FIG. 4.

As illustrated in FIG. 7, the manufacturing method of the CMOS imagesensor including a color microlens according to the present inventionincludes a step (S710) of forming a photodetection layer, a step (S720)of forming an anti-reflective layer, and a step (S730) of forming acolor microlens layer.

The step (S710) of forming the photodetection layer and the step (S720)of forming the anti-reflective layer are equal to those described inFIG. 5.

In the step (S730) of forming the color microlens layer, the colormicrolens layer including at least one color microlens formed atpositions respectively corresponding to the at least one photodiode isformed on the anti-reflective layer.

As illustrated in FIG. 6 and FIG. 7, when a process of forming theover-coating layer is omitted and the processes of forming the colorfilter and the microlens are integrated with each other, since aprocedure is simplified and the entire heights of the color filter layerand the microlens layer are reduced, optical properties are improved andinterfaces among the color filter layer, the over-coating layer, and themicrolens layer disappear, so that it is possible to further increaselight efficiency.

Although a preferred embodiment of the present invention has beendescribed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and the spirit of theinvention as disclosed in the accompanying claims.

1. A CMOS image sensor including a color microlens, comprising: aphotodetection layer formed over a semiconductor substrate and includingat least one photodiode for receiving light of at least one color; ananti-reflective layer formed over the photodetection layer; a colorfilter layer formed over the anti-reflective layer and including atleast one color filter formed at positions respectively corresponding tothe at least one photodiode; an over-coating layer formed over the colorfilter layer and including at least one over-coating formed at positionsrespectively corresponding to the at least one color filter; and a colormicrolens layer formed over the over-coating layer and including atleast one color microlens formed at positions respectively correspondingto the at least one color filter.
 2. A CMOS image sensor including acolor microlens, comprising: a photodetection layer formed over asemiconductor substrate and including at least one photodiode forreceiving light of at least one color; an anti-reflective layer formedover the photodetection layer; and a color microlens layer serving as acolor filter formed over the anti-reflective layer and including a colormicrolens serving as at least one color filter formed at positionsrespectively corresponding to the at least one photodiode.
 3. A CMOSimage sensor including a color microlens, comprising: a photodetectionlayer formed over a semiconductor substrate and including at least onephotodiode for receiving light of at least one color; an anti-reflectivelayer formed over the photodetection layer; and a color microlens layerformed over the anti-reflective layer and including at least one colormicrolens formed at positions respectively corresponding to the at leastone photodiode.
 4. The CMOS image sensor including the color microlensof claim 1, wherein the at least one color includes blue, green, and redcolors, respectively.
 5. The CMOS image sensor including the colormicrolens of claim 1, wherein the at least one color includes cyan,magenta, and yellow, respectively.
 6. The CMOS image sensor includingthe color microlens of claim 1, wherein a color of the at least onecolor filter and a color of the at least one color microlenscorresponding to the color are equal to or different from each other. 7.A manufacturing method of a CMOS image sensor including a colormicrolens, comprising the steps of: forming a photodetection layerincluding at least one photodiode for receiving light of at least onecolor over a semiconductor substrate; forming an anti-reflective layerover the photodetection layer; forming a color filter layer including atleast one color filter at positions respectively corresponding to the atleast one photodiode over the anti-reflective layer; forming anover-coating layer including at least one over-coating formed atpositions respectively corresponding to the at least one color filterover the color filter layer; and forming a color microlens layerincluding at least one color microlens formed at positions respectivelycorresponding to the at least one color filter over the over-coatinglayer.
 8. A manufacturing method of a CMOS image sensor including acolor microlens, comprising the steps of: forming a photodetection layerincluding at least one photodiode for receiving light of at least onecolor over a semiconductor substrate; forming an anti-reflective layerover the photodetection layer; and forming a color microlens layerserving as a color filter and including a color microlens serving as atleast one color filter formed at positions respectively corresponding tothe at least one photodiode over the anti-reflective layer.
 9. Amanufacturing method of a CMOS image sensor including a color microlens,comprising the steps of: forming a photodetection layer including atleast one photodiode for receiving light of at least one color over asemiconductor substrate; forming an anti-reflective layer over thephotodetection layer; and forming a color microlens layer including atleast one color microlens formed at positions respectively correspondingto the at least one photodiode over the anti-reflective layer.
 10. Themanufacturing method of the CMOS image sensor including the colormicrolens of claim 7, wherein in the step of forming the color microlenslayer, thicknesses of the at least one color microlens are formed to beequal to or different from each other.
 11. The CMOS image sensorincluding the color microlens of claim 2, wherein the at least one colorincludes blue, green, and red colors, respectively.
 12. The CMOS imagesensor including the color microlens of claim 3, wherein the at leastone color includes blue, green, and red colors, respectively.
 13. TheCMOS image sensor including the color microlens of claim 2, wherein theat least one color includes cyan, magenta, and yellow, respectively. 14.The CMOS image sensor including the color microlens of claim 3, whereinthe at least one color includes cyan, magenta, and yellow, respectively.15. The manufacturing method of the CMOS image sensor including thecolor microlens of claim 9, wherein in the step of forming the colormicrolens layer, thicknesses of the at least one color microlens areformed to be equal to or different from each other.